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111.
An adaptive optical system with a subjective feedback loop is used to improve the visual acuity and to determine the aberrations of the human eye. Corrections of as many as 12 low-order aberration modes were made, based on the perceived sharpness of the test object observed through the adaptive optical system. The acuity of vision was improved by adjustment of the weights of the orthogonal modes produced by a deformable mirror. Objective measurements of the correcting aspherical figures, obtained in independent subjective correction cycles for one person, demonstrated good repeatability. Participants in the study with strong ocular aberrations reported moderate to significant improvement of their visual acuity, estimated with the U.S. Air Force 1951 acuity chart. 相似文献
112.
A scheme for active phase stabilization and absolute positioning in Fourier-transform two-dimensional (2D) IR spectroscopy is presented. The position accuracy is better than 20 nm(rms) corresponding to lambda/250 at 5 microm, which significantly improves the quality of Fourier-transform 2D IR spectra. Phase stabilization is added to a standard photon echo setup in a way that does not impair the flexibility of the experiment and the control over IR pulse parameters. 相似文献
113.
A.?E.?DorokhovEmail author A.?E.?Radzhabov M.?K.?Volkov 《The European Physical Journal A - Hadrons and Nuclei》2004,21(1):155-159
The electromagnetic radius of a charged pion and the transition radius of a neutral pion are calculated in the framework of the nonlocal chiral quark model. It is shown in this model that the vector meson contributions to the pion radii are noticeably suppressed in comparison with a similar contribution in the local Nambu-Jona-Lasinio model. The form factor for the process
is calculated for -1 GeV2< q
2 < 1.6 GeV2. Our results are in satisfactory agreement with experimental data.Received: 28 November 2003, Published online: 13 July 2004PACS:
14.40.-n Mesons - 11.10.Lm Nonlinear or nonlocal theories and models - 12.39.Ki Relativistic quark model 相似文献
114.
We present a new Fourier-based exact solution for deterministic phase unwrapping from experimental maps of wrapped phase in the presence of noise and phase vortices. This single-step approach has superior performance for images with high phase gradients or insufficient digital sampling approaching 2pi/pixel and therefore performs as a fast and practical solution for the phase-unwrapping problem for experimental applications in applied optics, physics, and medicine. 相似文献
115.
We derive the magnetic transport-of-intensity equation (MTIE) that links defocused contrast of magnetic nanoobjects imaged by partially coherent electron waves to their micromagnetic parameters. This provides Maxwell's explanation for observable contrast in terms of the Z component of currents existing around vortices in superconductors and domain vortices and walls in ferromagnets. The solution of the MTIE via Fourier transform is used for quantitative mapping of magnetic flux and projected induction in magnetic and superconducting materials imaged by Lorentz microscopy. 相似文献
116.
Cho CH Hong YS Kang K Volkov VI Skirda V Lee CY Lee CH 《Magnetic resonance imaging》2003,21(9):1009-1017
The water self-diffusion behavior in chlorella water suspension was investigated by pulsed field gradient NMR technique. Three types of water was determined, which differs according to the self-diffusion coefficients; bulk water, extracellular and intracellular water. Intracellular and extracellular water self-diffusion were restricted, and the sizes of restriction regions were 3.4 microm and 17 microm, respectively. The water molecular exchange process between these three diffusion regions was investigated. The residence time and exchange rate constant for chlorella cells were obtained. The cell wall permeability determined from the rate constant as 3 x 10(-6) m/s agreed with the permeability 10(-6) m/s obtained from time dependence of intracellular water self-diffusion coefficient. The structural cluster model of chlorella cell is estimated to describe the extracellular water self-diffusion in chlorella water suspension. 相似文献
117.
A rearrangement of the ground state of a Wannier-Mott exciton upon an increase in its momentum is considered. The phase diagram of the electron and the hole experiencing the Coulomb interaction on the magnetic momentum-external magnetic field plane is investigated. A jumplike exciton-magnetoexciton “phase” transition is observed upon an increase in the momentum in fields B weaker than a certain value B<B tr1. As momentum P increases above a certain critical value P tr(B), the ground state of the system changes from the hydrogen-like state polarized by the Lorentz force to the magnetoexciton state in which the average distance 〈 r〉 between the electron and the hole increases jumpwise in the transverse direction relative to the field. As the exciton momentum increases, its wave function is extended along the magnetic field, acquiring the shape of a strongly prolate ellipsoid. It is interesting that the momentum of the transition tends to a finite value P 0>0 even for B→0. At the point of transition, the exciton energy-momentum relation changes jumpwise from a quadratic law to a relation virtually independent of the momentum. For B<B tr1, the exciton-magnetoexciton transition becomes blurred. 相似文献
118.
V. V. Volkov K. G. Myakishev P. P. Bezverkhii V. G. Martynets É. V. Matizen 《Journal of Structural Chemistry》2003,44(1):163-168
Theoretical predictions of hightemperature superconductivity (HTSC) in titanium borides, TiBk, have been experimentally verified. These predictions have been reported previously in the form of theoretical phase diagrams. They predicted the existence of HTSC in TiB
k
(1.43 < k < 2.57) phases and in TiB1.5–1.6. An abrupt decrease at 110 K was found on the temperature curve of conductivity R(T) for titanium samples whose surfaces were coated with diffuse layers of depthvariable boride compositions TiB
k
. This indicates that the layers include phases possessing HTSC. This behavior of the R(T) curves is explained assuming that the inclusions of HTSC phases have a strong effect on the resistance of the composite materials at Tc. The composition of the boride layers has been investigated by mass spectrometry. Diffuse boride layers were applied to titanium surface by treating its surface with a B2H6 + H2 gas mixture at 610–700°C followed by annealing in vacuum. 相似文献
119.
Kociak M Kasumov AY Guéron S Reulet B Khodos II Gorbatov YB Volkov VT Vaccarini L Bouchiat H 《Physical review letters》2001,86(11):2416-2419
We report measurements on ropes of single-walled carbon nanotubes (SWNT) in low-resistance contact to nonsuperconducting (normal) metallic pads, at low voltage and at temperatures down to 70 mK. In one sample, we find a 2 orders of magnitude resistance drop below 0.55 K, which is destroyed by a magnetic field of the order of 1 T, or by a dc current greater than 2.5 microA. These features strongly suggest the existence of superconductivity in ropes of SWNT. 相似文献
120.
V. V. Volkov G. G. Adamian N. V. Antonenko E. A. Cherepanov W. Scheid 《Physics of Atomic Nuclei》2001,64(6):1116-1120
The development of various approaches to describing the complete fusion of nuclei and their connections with experimental studies is discussed. A brief account of the dinuclear-system concept (DNSC), the approach proposed at Dubna, is given. The DNSC revealed two important features of the complete fusion of massive nuclei: the existence of the inner fusion barrier B fus * and the competition between complete fusion and quasifission channels in a dinuclear system formed at the capture stage. The DNSC was applied to the analysis of reactions used to synthesize superheavy elements (SHE). The DNSC provided a basis for the models of competition between complete-fusion and quasifission channels. Using these models, one can describe the cross section for SHE production in cold-and warm-fusion reactions. 相似文献